Acting Seattle Mariners manager Robby Thompson is finding out firsthand just how difficult life in the hot seat can be. After watching his squad drop a heartbreaker in 15 innings to the Boston Red Sox on Wednesday, Thompson, who's filling in for manager Eric Wedge as he recovers from a minor stroke, had to suffer through another painful experience on Thursday right as he contributed to the Mariners ninth inning meltdown with a costly rookie mistake.

It happened as Thompson came out of the dugout to yank closer Tom Wilhelmsen after he allowed each of the first four batters in the inning to reach base. His intention was to call on right-hander Yoervis Medina, but his first signal was a raise of the left arm. He caught his mistake quickly and immediately began pointing to his right arm.

However, with left-handed reliever Oliver Perez also warming up, third base umpire Gary Darling ruled that he was committed to the left-hander.

"We wanted to go to Medina there and if we had to go to Ollie, he was the next guy," said Thompson. "If there was anything today for me, it was a lesson learned that if you make a motion with either hand, that's it. I didn't realize that.

"I did point to the pen, but I didn't have time to [tap his other arm] for the right-hander," Thompson said. "He'd already turned. That's when I wanted to make sure he knew who I wanted to go to and [crew chief] Gary Darling said it's too late, you raised your left hand up."

Personally, I think it's ridiculous that umpires can't be more flexible with this rule. It's not as if Thompson changed his mind halfway through the change, he simply made a mistake and then corrected it before he'd even reached the hill or taken the ball from his closer.

Not surprisingly, the mishap would prove costly for Thompson as Perez immediately allowed singles to right-handed hitters Shane Victorino and Dustin Pedroia. When Perez finally faced David Ortiz, the man he had been preparing to face all along, he got the strikeout. But the damage was already done and the inning was already spiraling out of control. Following the strikeout, Thompson finally did call on Medina. Three batters later, the game was over after Daniel Nava delivered a walk-off single to win it 8-7.

In total, the disaster inning featured three different pitchers for Seattle, 10 batters for Boston, six runs, six hits, three walks and only one out recorded.

At the end of the day, Thompson may have erred in embarrassing fashion, but it doesn't seem like his bullpen was interested in cooperating anyway.